Understanding Hyperledger Composer Query Language
Hyperledger Composer is a very popular Blockchain application development, the popularity is mainly because of it's ease of use. Learn more.
Karthik Kamalakannan
Founder and CEO
One of the key component is the Query language which resembeles SQL language. In this article I’ll go through how we can build queries for your blockchain application.
In current version of Hyperledger Fabric, the LIMIT and SKIP is not supported it is so in Composer too.
The data model
For this example, I’ll consider the following data model as our application’s data model.
Queries
Get the users based on role. In order to get the list of users based on their roles, we can use the where filter
Also you can give the value from paramater as below
Get users based on organization To get the nodes based on their related or associated files you can use the where with following type
Get Products with quantity more than minimal threshold We can use greater than or lesser than operators in integer or double values as follows.
Using AND operator
Using ORDER BY operator
Using CONTAINS operator
Mostly you can do all the quering with the above mentioned operators, and also I think there will be even more complex queries in the future.
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